The present invention has as its object a grain thresher for cereals, and particularly for millet, sorgho, paddy and similar.
The shape of the ears of millet (souana-sanio), the lay-out of the grains on the rachis, the strength of the pedicels, the characteristics of the involucre are factors which must be taken into consideration in determining a threshing principle different from the conventional principles of threshers for cereals such as wheat, maize, oats barley etc...
A known process consists in directing the ears by means suction in front of a driving drum towards a thresher and counter-thresher unit where the ears rolling on themselves are progressively compressed between a fixed surface and a movable surface covered with an abrasive material such as expended metal, then towards a distributing paddle drum housed in a closed space where the coarse waste is separated, and finally on to a rotary sieve eliminating the straw and leaving the grains to flow towards the elevator screw against the flow of air in a ventilation passage with adjustable deflector.
A major disadvantage of such an installation is that the ears have a tendency to jam up between the routing drum and the thresher despite the ventilation; moreover, the ventilation towards the sieve is insufficient to eliminate all the waste.